1. Field of the Invention
The present invention relates to lens systems for refracting and distributing emitted light and particularly relates to lens systems allowing change in the refraction and distribution characteristic of light emitted from a lighting fixture.
2. Discussion of the Prior Art
Exterior vehicle lighting including the efficient generation, distribution, or direction of lighting facilitates both the ability for the driver to see, and for the vehicle to be seen, in low ambient light conditions. Selection or design of vehicle lighting component including without limitation, the light source, reflector(s), and lens, controls the ability to direct and distribute light. Filament lighting is an appropriate light source in some applications, but alternate light sources, including Light Emitting Diodes (LEDs), also find favor in certain applications of vehicle lighting systems as LEDs present advantages over filament based lamp lighting.
Filament based lamp lighting has inherent drawbacks. First, a significant portion of the light generated from a filament light radiates outward and must be redirected by reflectors and a Fresnel or collimating lens design. Fresnel lenses include annular portions including an inner lens portion inside an outer lens portion wherein the outer lens portion will have incrementally steep lens portion precisely stepped to facilitate the focusing of light rays emitted at a greater angle of incidence from the light source. Second, filament lighting provides but one source of light. If the bulb ruptures or filament expires, the light source loses all utility. Hence the need for alternate light sources.
The use of LEDs however also presents challenges related to directing or distributing generated light. One challenge is the relative brightness of a typical single LED, which is significantly less than a capable filament based bulb and less than required for a vehicle lamp. LEDs are therefore included in plurality to generate sufficient light and match the light production of prior art filament type vehicle lamps. But, several or a plurality of LEDs generate light from multiple points rather than one and the LED lighting system designer must therefore consider the direction or distribution of light emitted from a plurality of LED sources. Accordingly, the art includes solutions to problems concerning the direction or distribution of light generated from a plurality of LEDs.
As examples, U.S. Pat. Nos. 7,766,509 and 7,959,326 disclose a base structure for mounting a plurality of LEDs where the base structure has a plurality of orientable lenses each individually affixed about a single LED. Each orientable lens is securely attached to the base structure and has a primary reflector and a refracting lens that direct light emitted from a single LED. Similarly, U.S. Pat. No. 8,029,157 discloses a LED light fixture having multiple refractory lenses positioned relative to and directly above light sources. The multiple lenses are connected to the circuit board or base that secures the LED light source modules.
U.S. Pat. No. 7,153,000 discloses a multi-lens LED with an intermediate layer positioned between the multiple lenses in order to radiate light emitted from an LED chip in a desired direction and/or at a desired beam angle. A first lens is centered behind the LED chip. The second lens has a concave structure and surrounds the first lens and an intermediate layer is interposed between the first and second lenses, so that light emitted from the LED chip can be radiated at a wide beam angle.
The aforementioned patents disclose devices that are suited for a particular purpose and disclose appropriate solutions for that purpose. Each patent discloses a light system that includes directing the light from individual LEDs by using one or more lenses secured relative to a light source. It would be advantages to have a light system and components that allows changing the projection direction of light or its diffusion, or creating portions of directed or diffused light and changing the portions thereof.